The present invention relates to apparatus for imaging photographic film or the like, and more particularly, to an exposure slit having a light reflection hood to reduce film fogging. As used herein, the term xe2x80x9cfilmxe2x80x9d is intended to mean any type of image recording media that is responsive to light, including photographic film, dye transfer media and the like, and is not to be construed only as photographic film.
In order to record high quality images on photographic film or other media for the production of movies or slides, film recorders are used. In a conventional film recorder, a light beam from a cathode ray tube (xe2x80x9cCRTxe2x80x9d), laser apparatus, or the like is controlled by a deflection system to scan across a stationary frame of photographic film to expose the film with an image. Typically, the images are generated by a computer for the production of slides, transparencies, photographs or the like. Alternatively, the images can comprise natural images acquired by a scanner or television camera for subsequent processing by a computer.
Known film recorders, such as those sold under the trademark SOLITAIRE(copyright) by Management Graphics, Inc. of Minneapolis, Minn., U.S.A., typically include a light source such as a CRT for producing a beam, a deflection system for scanning the beam across the face of the CRT, a system control and central processor unit (xe2x80x9cCPUxe2x80x9d) for controlling the deflection system, and a camera (i.e., xe2x80x9cfilm transportxe2x80x9d). The later component may include a film transport body, lens, lens mounting assembly, aperture plate, film plate and film transport mechanism.
On a SOLITARE(copyright) film recorder, an image to be recorded is first written on the phosphor of the CRT by deflecting an electron beam in a raster pattern and modulating the intensity of the beam. This process is analogous to the creation of a television picture. Alternatively, the image can be written on the CRT using well-known time modulation techniques, wherein the beam intensity is constant but the time the beam is kept at each point is varied depending on the exposure required.
The resulting pattern (xe2x80x9cthe object imagexe2x80x9d) on the CRT is optically imaged onto photographic film or the like by the film transport, which contains the required optics and mechanism to advance the film to successive frames. Other types of light sources can be substituted for the CRT in a film recorder. Examples include fiber optic sources, lasers and focused light impinging a rotating drum wherein one or more rotations are completed for each scanned line.
One problem that has arisen when light is scanned onto the film one line at a time is that the light for one line will bleed over into other lines. This results in fogging of the image or a halo effect that is detrimental to the final image.
As technology has improved, film recorders have been steadily getting faster in order to reduce imaging time. A requirement of this faster performance is that the cathode ray tube (or other light source) used in the film recorder must produce more light. As a result of having more light, the unwanted portion of light that bounces around inside of the film recorder due to the light source, filters, lenses, the camera box and film surface becomes more significant. This increases the problem of fogging referred to above.
The use of an exposure slit to reduce fogging in an image recording apparatus is known. For example, U.S. Pat. No. 5,640,228 discloses an exposure slit for a shuttle style film gate in a film transport. The exposure slit is provided on a plate that is mounted to the film gate shuttle. After the shuttle advances a frame of the film, it carries the slit with it during its return to a home position. Exposure of the film frame is made through the slit during the return travel.
Current generations of film recorders using such a slit can still suffer from fogging due to the increased light used to reduce imaging time. Thus, it would be advantageous to provide an improved exposure slit to reduce undesirable light from fogging the image on the film. It would be advantageous for such a slit to also create higher contrast and dynamic range. Such improvements will result in more vivid colors and clarity in the final image.
The present invention provides an improved exposure slit having the aforementioned and other advantages.
In accordance with the present invention, an exposure slit is provided for an image recording apparatus. The exposure slit includes a plate having an opening for the passage of light. First and second inclined walls extend toward each other from the plate to form a slit over the opening. The slit formed by the inclined walls is narrower than the opening, and the walls function as a light reflection hood.
The inclined walls can be formed either from a portion of the plate material itself, e.g. by punching and/or bending the plate material, or can be separate pieces attached to the plate. In a preferred embodiment, the inclined walls are sharply pointed at edges forming the slit.
The inclined walls may have opposing flat surfaces that face each other to form the slit, with the flat surfaces being perpendicular to the plate. Alternatively, the inclined walls may have opposing undercut surfaces that face each other to form the slit. In such an embodiment, the undercut surfaces are generally perpendicular to the plate.
An image recording apparatus is also provided for exposing a recording medium with radiation from an imaging source. The image recording apparatus comprises a plate having an elongated opening arranged in proximity to the recording medium. First and second inclined walls extend toward each other from the plate to form a slit over the opening for passing radiation to the recording medium. The slit is narrower than the opening. Transport means can be provided to drive the plate along the recording medium, thereby allowing exposure of different regions of the recording medium via the slit.
A plate is provided having an opening for the passage of light therethrough for use in conjunction with the recording medium in an image recording apparatus. First and second inclined walls extend toward each other from the plate to form a slit over the opening. This slit is narrower than the opening in the plate. The plate is mounted for movement along at least a portion of the recording medium, with the exposure slit being adjacent to the portion of the recording medium. Radiation is passed to the recording medium portion via the slit during an image scanning operation.